521555134464 has 1728 divisors, whose sum is σ = 2091323707200. Its totient is φ = 127529385984.

The previous prime is 521555134421. The next prime is 521555134469. The reversal of 521555134464 is 464431555125.

521555134464 is a `hidden beast` number, since 5 + 2 + 1 + 5 + 55 + 134 + 464 = 666.

It is a tau number, because it is divible by the number of its divisors (1728).

It is a super-2 number, since 2×521555134464² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (521555134469) by changing a digit.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 7784404959 + ... + 7784405025.

It is an arithmetic number, because the mean of its divisors is an integer number (1210256775).

Almost surely, 2^521555134464 is an apocalyptic number.

521555134464 is a gapful number since it is divisible by the number (54) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 521555134464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1045661853600).

521555134464 is an abundant number, since it is smaller than the sum of its proper divisors (1569768572736).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

521555134464 is a wasteful number, since it uses less digits than its factorization.

521555134464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 155 (or 109 counting only the distinct ones).

The product of its digits is 1440000, while the sum is 45.

Adding to 521555134464 its reverse (464431555125), we get a palindrome (985986689589).

The spelling of 521555134464 in words is "five hundred twenty-one billion, five hundred fifty-five million, one hundred thirty-four thousand, four hundred sixty-four".